JP2007021286A - Method for treating waste water containing organic phosphorous compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating waste water capable of efficiently removing a phosphorous compound from the waste water and further reducing the amount of diluting water used for diluting a phosphorous content in the waste water to an amount not more than a regulated reference value. <P>SOLUTION: The method for treating the waste water containing an organic phosphorous compound comprises a process for loading a calcium compound into the waste water containing a compound having general formula (1) generated when a compound having general formula (2) is produced, wherein in formula (1) and formula (2), R<SP>1</SP>, R<SP>2</SP>, R<SP>3</SP>, R<SP>4</SP>and R<SP>5</SP>independently represent a hydrogen atom, a lower alkyl group, a cycloalkyl group, an aryl group or an aralkyl group respectively, however, the case when both R<SP>1</SP>and R<SP>2</SP>are the hydrogen atom, and the case when R<SP>3</SP>, R<SP>4</SP>and R<SP>5</SP>are equally the hydrogen atom are excluded, having a pH of an alkaline area to dissolve it, and crystallizing by reaction with the organic phosphorous compound and calcium compound; a process for adding sodium chloride to make a reaction crystallization substance into a coarse particle by salt precipitation; and a process for filtering to remove the coarse particle substance. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for treating waste water containing an organophosphorus compound.

  When wastewater containing phosphorus is discharged into closed waters such as lakes, it becomes a source of eutrophication and causes deterioration of water quality. With increasing environmental awareness, the phosphorus content in wastewater is strictly regulated. For this reason, when there is a large amount of phosphorus in the waste water, dilute with diluted water so that the phosphorus content of the waste water is below the reference value before discharge, or take measures such as removing phosphorus compounds from the waste water in advance. There is a need.

  In general, biological treatment methods, coagulation sedimentation methods, adsorption methods, crystallization methods, and the like are known as methods for removing phosphorus compounds contained in waste water before discharge, and among these, they are discharged out of the system. A crystallization method that can reduce the amount of phosphorus-containing material has attracted attention.

For example, Patent Document 1 discloses that a hydroxyapatite-like substance is precipitated by adding a calcium compound and an alkali metal hydroxide into waste water containing phosphorous acid or a salt thereof, and the pH of the precipitate is further adjusted to about neutral. In addition, a method of precipitating and removing phosphorous acid or a salt thereof by filtering it with weak alkalinity is described.
Further, Patent Document 2 discloses a method of crystal growth using phosphine ore pulverized in the crystallization process of the crystallization method as a crystal seed, and a phosphorus-containing wastewater having a pH value of 9 to 11 in the presence of calcium ions. A method of increasing the crystal growth point and promoting the precipitation reaction by bringing calcium phosphate precipitated in the range of (1) into contact with the inorganic porous body and trapping it in the pores of the inorganic porous body is described.
Japanese Patent Laid-Open No. 9-24378 JP 2003-94071 A

  In a factory that manufactures an organic phosphate compound, wastewater containing an organic phosphorus compound is generated when the compound is manufactured. However, unlike inorganic phosphorus compounds such as phosphate ions and phosphite ions, it is difficult to remove phosphorus compounds by crystallization using organic phosphorus compounds. Technology development that can improve efficiency is desired.

  For this reason, conventionally, when discharging wastewater containing an organophosphorus compound, the wastewater is treated in advance by adding ferric chloride, which is an iron-based flocculant, and further diluted water is added to dilute the wastewater. The phosphorus content was below the regulation standard value. However, wastewater after iron salt treatment has a tendency to be colored yellow, and in iron salt treatment, organic phosphorus compounds in the wastewater are difficult to form a precipitate, so there is a problem that the efficiency of removing phosphorus is low. .

  When diluting with dilution water, if the phosphorus content in the wastewater is large, the amount of dilution water for reducing the regulated value or less is inevitably increased, resulting in a problem of increased wastewater treatment costs. For this reason, an effective technique that can efficiently remove the organophosphorus compound from the waste water before the discharge is desired so that the production plant of the organophosphate ester compound can be used in a small amount.

  The present invention has been made in view of the above circumstances, and it is an object to provide a wastewater treatment method for efficiently removing an organic phosphorus compound contained in wastewater when producing an organic phosphate ester compound. To do.

As a result of intensive studies to solve the above problems, the present inventors have completed the present invention. The present invention collectively includes the following inventions.
In the invention according to claim 1, the pH of the wastewater containing the organophosphorus compound represented by the general formula (1), which is generated during the production of the organophosphate ester compound represented by the general formula (2), is set in the alkaline region. Adding and dissolving the calcium compound to react and crystallize the organophosphorus compound and the calcium compound; adding sodium chloride to coarsen the reaction crystallized product by salting out; and filtering and removing the coarse particleized product. It is a processing method of the waste_water | drain containing the organic phosphorus compound characterized by consisting of a process.

(In Formula (1), R ¹ and R ² each independently represents a hydrogen atom, a lower alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, provided that both R ¹ and R ² are hydrogen atoms. If it is an atom, it is excluded.)

(In the formula (2), R ³ , R ⁴ and R ⁵ each independently represents a hydrogen atom, a lower alkyl group, a cycloalkyl group, an aryl group or an aralkyl group, provided that R ³ and R ⁴ Excludes when both R ⁵ are hydrogen atoms.)

  Invention of Claim 2 is the processing method of the waste_water | drain containing the organophosphorus compound of Claim 1 whose said organophosphate ester-type compound is an orthobiphenyl diphenyl phosphate composition.

The invention according to claim 3 is characterized in that the waste water to be treated contains, in addition to the organophosphorus compound represented by the formula (1), another phosphorous compound different from the organophosphorus compound. A wastewater treatment method containing the organophosphorus compound according to 1 or 2.
Invention of Claim 4 is a processing method of the waste_water | drain containing the organic phosphorus compound of Claim 3 characterized by the said other phosphorus compound being orthophosphoric acid or phosphorous acid.

The invention according to claim 5 contains the organophosphorus compound according to any one of claims 1 to 4, wherein the pH of the waste water when adding the calcium compound is 8 to 12. This is a wastewater treatment method.
Invention of Claim 6 is a processing method of the waste_water | drain containing the organophosphorus compound as described in any one of Claims 1-5 whose said calcium compound is calcium chloride.
The invention according to claim 7 is characterized in that the molar ratio of the phosphorus compound in the waste water to be treated and the calcium compound added to the waste water is 1: 1.7 to 1: 2.0. It is the processing method of the waste_water | drain containing the organophosphorus compound as described in any one of 1-6.

The waste water treatment method of the present invention is a calcium compound in an alkaline region with respect to waste water containing an organophosphorus compound of the general formula (1) that is generated during the production of the organophosphate compound represented by the general formula (2). The first step is to add and dissolve this, and by adopting this step, reaction crystallization of the calcium compound and the phosphorus compound occurs. Next, salting out by adding salt is the second step. By adopting this salting-out step, the crystallized product that has been precipitated and grown in the first step can be further coarsened. Furthermore, filtering and removing is the third step, and in this step, the coarse particles are removed from the discharged waste water.
Since the present invention has the above three steps as constituents, the crystallization rate, precipitation growth rate, coarse particle formation and filtration efficiency of the organophosphorus compound of general formula (1) and the calcium compound are high, and as a result The removal efficiency of phosphorus is as high as 98% or more.

Hereinafter, the best mode for carrying out the present invention will be described.
In the present invention, the organophosphorus compound intended to be removed from waste water is an acidic ester of normal phosphoric acid corresponding to the above general formula (1), or a mixture of one or more. In the formula (1), R ¹ and R ² each independently represent a hydrogen atom, a lower alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group. However, the case where both R ¹ and R ² are hydrogen atoms (normal phosphoric acid) is excluded because it is not an organic phosphorus compound.

In the present invention, the organophosphorus compound represented by the general formula (1) is an organophosphorus compound generated during the production of the organophosphate compound represented by the general formula (2). Here, the organic phosphate ester-based compound is a neutral ester and / or acidic ester of normal phosphoric acid corresponding to the general formula (2), or a mixture of one or more types. In the formula (2), R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom, a lower alkyl group, a cycloalkyl group, an aryl group or an aralkyl group. However, the case where R ³ , R ⁴ and R ⁵ are all hydrogen atoms (normal phosphoric acid) is excluded because it is not an organic phosphate ester compound.

In the above formulas (1) and (2), the lower alkyl group is a linear or branched alkyl group having 1 to 4 carbon atoms. Specific examples include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group and the like.
Examples of the cycloalkyl group include a cyclohexyl group and a 3-methylcyclohexyl group.
Examples of the aryl group include a phenyl group, an orthobiphenyl group, a parabiphenyl group, a tolyl group (also referred to as cresyl group), and a naphthyl group.
Furthermore, examples of the aralkyl group include a benzyl group and a phenethyl group.

Although this invention is not specifically limited, An orthobiphenyl diphenyl phosphate composition is mentioned as a specific example of the organophosphate type compound of General formula (2). Here, the orthobiphenyl diphenyl phosphate composition is composed of four components, triphenyl phosphate, orthobiphenyl diphenyl phosphate, bis (orthobiphenyl) phenyl phosphate, and tris (orthobiphenyl) phosphate. Among these, orthobiphenyl diphenyl phosphate is It is a composition which is a main component.
Other examples of the organic phosphate ester compound corresponding to the general formula (2) include trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, tricresyl phosphate, and diphenyl cresyl phosphate. It is done.

When producing the organophosphate compound of the general formula (2), waste water containing the organophosphorus compound of the general formula (1) is generated. For example, in the case of an orthobiphenyl diphenyl phosphate composition, R ³ , R ⁴ and R ⁵ are each independently an orthobiphenyl group or a phenyl group. The wastewater generated in this case contains an organophosphorus compound in which R ¹ and R ² are each independently an orthobiphenyl group, a phenyl group, or a hydrogen atom in the general formula (1).

  The phosphorus concentration in the wastewater containing the organic phosphorus compound of the general formula (1) is distributed in the range of several hundred ppm to several percent, and in particular, the range of 500 ppm to about 5% is the wastewater treatment of the present invention. Desirable to apply the law.

The wastewater containing the organic phosphorus compound of the general formula (1) contains wastewater containing other phosphorus compounds such as orthophosphoric acid (H ₃ PO ₄ and its ions) and phosphorous acid (H ₃ PO ₃ and its ions). The wastewater treatment method of the present invention can also be applied to wastewater mixed with. The present invention can be applied to any weight ratio between the organic phosphorus compound and the inorganic phosphorus compound in the waste water after mixing.

As the calcium compound used in the wastewater treatment method of the present invention, calcium oxide, calcium hydroxide, calcium chloride and the like can be used. Of these, calcium chloride (CaCl ₂ ), which is a water-soluble calcium compound, is most preferable. In the crystallization method, the amount of calcium compound added is theoretically 1.7 moles of calcium relative to 1 mole of phosphoric acid, particularly preferably about approximately from the molecular formula Ca ₁₀ (PO ₄ ) ₆ (OH) _{2 of} hydroxyapatite. Two moles of calcium are required.

  Therefore, in the present invention, when a calcium compound is added to the organophosphorus compound represented by the general formula (1), the necessary lower limit value can be estimated from the amount of calcium used in the conventional method. That is, the molar ratio of the calcium compound to be added to the phosphorus compound in the wastewater to be treated is a molar ratio (1: 1.7 to 1: 2. The range 0) is preferred.

  Depending on the assumed phosphorus removal rate, the amount of calcium compound added per mole of phosphorus compound may be less than 1.7 moles. In addition, if the amount of calcium compound added per mol of phosphorus compound exceeds 2.0 mol, the removal rate of the phosphorus compound is not particularly adversely affected, but from an economical point of view, the added amount should not be excessive. Is desirable. Even if the addition amount of the calcium compound per mol of the phosphorus compound is increased to, for example, 3 mol or 4 mol, the excess calcium content does not contribute to the phosphorus removal rate, and the phosphorus concentration in the filtrate hardly changes.

  Crystallization due to the reaction between the calcium compound and the organophosphorus compound represented by formula (1) occurs when the pH is 8 or higher. Therefore, when the pH of the wastewater is less than 8, the pH of the wastewater is previously set to pH 8 with an alkali. It is desirable to add the calcium compound after adjusting to a range of ˜12, particularly preferably around pH 10. In the present invention, examples of the alkali (alkaline substance) used for adjusting the wastewater to be alkaline include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide.

  When the pH of the wastewater is adjusted to the alkaline region, preferably in the range of pH 8 to 12, and the calcium compound is added and stirred, the reaction between the calcium compound and the phosphorus compound occurs under stirring conditions, and the system gradually becomes cloudy (crystallized). come. Incidentally, when the pH of the waste water when adding the calcium compound is less than 8, crystallization due to the reaction between the calcium compound and the phosphorus compound is insufficient, and the removal efficiency of the phosphorus compound cannot be increased.

  Moreover, when the crystallized substance is filtered and removed as it is after the calcium compound is added, the phosphorus compound cannot be sufficiently precipitated from the waste water, and the phosphorus removal rate is lowered. Therefore, in this invention, sodium chloride (salt) is further added and a salting-out process is performed. Thereby, the crystallized product precipitates and grows into coarse particles. By removing the coarse particles by filtration, the phosphorus removal rate of the wastewater containing the organic phosphorus compound can be greatly improved. The amount of salt added in the salting-out step is sufficient to bring the inside of the system close to saturated saline because a large excess of salt is not economically appropriate. After the addition of salt, stirring is preferably continued for 30 minutes to 1 hour within a range that does not affect workability.

  As described above, the calcium salt is generated in the alkaline region with respect to the wastewater containing the organophosphorus compound represented by the general formula (1) generated during the production of the organophosphate compound represented by the general formula (2). By performing the treatment, and further performing salting-out treatment and filtration removal, wastewater containing an organic phosphorus compound can be treated with good workability and an extremely high phosphorus removal rate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these examples. In the following examples, “%” and “ppm” represent mass percentage and mass percentage unless otherwise specified.

[Example 1]
(Production of organophosphate compounds)
In a 3 liter reactor equipped with a stirrer, thermometer, hydrochloric acid recovery device, and condenser (cooling water 5 ° C.), phenol 786.7 g (8.36 mol), orthophenylphenol 680.8 g (4 mol), oxychloride 613.2 g (4 mol) of phosphorus and 6 g of magnesium chloride were charged, and the temperature was raised from 130 ° C. to 190 ° C. over 8 hours.

  Thereafter, aging was carried out at a pot temperature of 190 ° C. and a vacuum degree of 100 torr for 2 hours, and then cooled to 100 ° C. under a nitrogen atmosphere to avoid coloring, thereby obtaining 1609.8 g of an orthobiphenyl diphenyl phosphate composition (hereinafter abbreviated as BDP). It was.

  After adding 1000 g of xylene to the BDP crude product, 300 g of an aqueous hydrochloric acid solution having a concentration of 5% by weight was added, followed by washing and stirring at 80 ° C. for 30 minutes. After standing for 30 minutes and separating the solution, 300 g of 10% aqueous sodium carbonate solution was added, neutralized and separated at 80 ° C., and further washed with 400 g of purified water at 80 ° C. Separated into product.

  The crude BDP product was heated at 150 ° C. for 2 hours from atmospheric pressure to 50 torr to remove the solvent, and then purified by distillation using a vacuum pump. As a result, the yield of BDP obtained was 1445.6 g. The rate was 88%.

(Treatment of wastewater containing organophosphorus compounds)
In order to treat 1000 g of wastewater (COD 25100 ppm, phosphorus concentration 1300 ppm) generated when producing BDP, which is an organic phosphate ester compound, 1.7 g of 48% sodium hydroxide aqueous solution was added to adjust the pH to 10. Then, 23 g of 35% calcium chloride aqueous solution was added under stirring conditions. As a result, a reaction between calcium chloride and the phosphorus compound in the wastewater occurred, and the mixture gradually became cloudy. This shows that a crystallized product was formed.

  Next, 308 g of sodium chloride was added, and a crystallized product was further precipitated and grown by a salting-out treatment to form coarse particles. After the addition of salt, stirring was continued for 30 minutes, and then the crystallized crystallized particles were filtered with a Nutsche having a diameter of 5 cm under reduced pressure by an aspirator. The filtrate was analyzed for COD and phosphorus concentration by the method described in JIS 0102. As a result, COD of 1000 ppm and phosphorus concentration of 0.4 ppm were obtained.

[Comparative Example 1]
As an organic phosphorus compound-containing wastewater, a 38.9% ferric chloride (FeCl ₃ ) aqueous solution under stirring conditions was used for 1000 g of wastewater (COD25100 ppm, phosphorus concentration 1300 ppm) generated in the production of BDP as in Example 1. When 1 g was added, coagulation precipitation occurred with the addition of the drug. Stirring was continued for 30 minutes after the addition of the drug, and thereafter, the stirring was stopped and the mixture was left to stand overnight. On the next day, the aggregated precipitate was filtered through a Nutsche having a diameter of 5 cm under reduced pressure by an aspirator. The filtrate was analyzed for COD and phosphorus concentration by the method described in JIS 0102. As a result, COD of 17000 ppm and phosphorus concentration of 800 ppm were obtained.

[Comparative Example 2]
As in the case of Example 1, wastewater (COD25100ppm, phosphorus concentration 1300ppm) 1000g as the organic phosphorus compound-containing wastewater was treated in the same manner until the addition of 48% aqueous sodium hydroxide and 35% aqueous calcium chloride. However, the precipitated crystals were removed by filtration without salting out with sodium chloride. That is, the precipitate was filtered with a Nutsche having a diameter of 5 cm under reduced pressure by an aspirator. The filtrate was analyzed for COD and phosphorus concentration by the method described in JIS 0102. As a result, COD 15000 ppm and phosphorus concentration 600 ppm were obtained.

[Comparison of results of Examples and Comparative Examples]
As shown in Table 1, in the examples, the COD and phosphorus concentration of the waste water could be greatly reduced. From this result, it is clear that the organophosphorus compound contained in the waste water can be efficiently removed by the present invention.

  According to the wastewater treatment method of the present invention, the phosphorus concentration in the filtrate after treatment can be drastically reduced as compared with the conventional one, and the phosphorus content in the discharged wastewater is made to be below the regulation standard value. The amount of dilution water used can be greatly reduced.

Claims (7)

The pH of the wastewater containing the organophosphorus compound represented by the general formula (1) generated during the production of the organophosphate compound represented by the general formula (2) is dissolved by adding a calcium compound in the alkaline region. It comprises a step of reacting and crystallizing an organophosphorus compound and the calcium compound, a step of adding sodium chloride to coarsen the reaction crystallized product by salting out, and a step of filtering and removing the coarsely particulated product. A method for treating wastewater containing an organophosphorus compound.

(In Formula (1), R ¹ and R ² each independently represents a hydrogen atom, a lower alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, provided that both R ¹ and R ² are hydrogen atoms. If it is an atom, it is excluded.)

(In the formula (2), R ³ , R ⁴ and R ⁵ each independently represents a hydrogen atom, a lower alkyl group, a cycloalkyl group, an aryl group or an aralkyl group, provided that R ³ and R ⁴ Excludes when both R ⁵ are hydrogen atoms.)   The method for treating wastewater containing an organophosphorus compound according to claim 1, wherein the organophosphate ester compound is an orthobiphenyl diphenyl phosphate composition.   The organophosphorus compound according to claim 1 or 2, wherein the waste water to be treated contains another phosphorus compound different from the organophosphorus compound in addition to the organophosphorus compound represented by the formula (1). Wastewater treatment method containing   The method for treating waste water containing an organophosphorus compound according to claim 3, wherein the other phosphorus compound is orthophosphoric acid or phosphorous acid.   The pH of the waste water at the time of adding the said calcium compound is 8-12, The processing method of the waste water containing the organophosphorus compound as described in any one of Claims 1-4 characterized by the above-mentioned.   The said calcium compound is calcium chloride, The processing method of the waste_water | drain containing the organophosphorus compound as described in any one of Claims 1-5 characterized by the above-mentioned.   The molar ratio between the phosphorus compound in the wastewater to be treated and the calcium compound added to the wastewater is from 1: 1.7 to 1: 2.0, according to any one of claims 1 to 6, The processing method of the waste_water | drain containing the organophosphorus compound of description.